Total mass of geochemical data from solid model

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Guest Tofer Lewis

Guest Tofer Lewis

Answer: 1. First determine the conversion factor. You need to determine the conversion factor to translate your measured units (parts per million, for example) into mass (pounds or kilos or tons) at the volume units you are using (cubic feet, cubic meters, etc.). It is all a matter of units.

2. Filter for Surface Elevations . You need to constrain the solid model based on the surface elevations. You might want to do this if your study area is not flat and the solid model (which does have a flat top) contains extrapolated values that lie above the ground surface. You can create suface models of the elevations in RockWorks. (Use the Borehole Manager's Stratigraphy > Structural Elevations if you have the ground, at zero depth, defined as the uppermost stratigraphic layer. Or use the Geological Utilities Map > Grid-Based Map to create a surface model of known X, Y, surface elevations.) Be sure the grid model has the same dimensions and node spacing as the X,Y dimensions of your solid model. (Tip: The View > Project Settings > Hardwire Project Dimensions tool can provide an easy way to be sure all models within a project maintain like-spacings).

To filter the solid model, use the Geological Utilities Solid > Filter > Grid Filters > One Bounding Grid option. Set the multiplier for above-grid nodes to 0 and that for the below-grid nodes to 1.

3. Run the Geochemisty Volumetrics by using the Borehole Manager's Geochemistry > Volumetrics tool to give the program the name of the existing geochemistry model (*.mod) and the name of the geochemical track in the data being represented.

4. Enter names for the Boolean model (which you may not use if you do not use any G value or spatial filtering) and the grid model (ditto) to be created.

5. Establish the data range you are interested in. This is important. If you want to compute total mass of all of the geochemistry values, use "0" for the low and "99999" for the high, or whatever values will completely encompass the G value range in the geochemical solid model. If you only want to compute mass for a specific G value range, then enter those values. You might, for example, only want to look at the values that fall within the scope of a remediation project.

6. Set the Interbed Filter > Thickness Filter as you wish, described in the program's abstracts and help messages. These allow you to qualify a node as a "keep-it' node versus a "pitch-it" node based on its proximity to other nodes, its location under overburden, etc. Again, if you are working with the whole plume, you might not invoke any of these filters.

7. Insert a check in the Density Conversion check-box, and expand it to enter the Conversion Factor that will translate volume units to mass units as determined in step 1.

8. Insert a check in the Create Report check-box, and expand it to establish the report settings. Be sure that the length units and mass units are entered with the text you wish to have displayed in the report. Check the Verbose setting if you want to see a more detailed listing of the volume computations.

9. The Create Solid Diagram and Create Grid Diagram options are helpful if you have activated any of the filtering options, which will result in a display of the distribution of geochem values that are still included in the computations.

Please see the Help messages for more detailed information about the volumetrics and mass computations.